widenconst before type check in SROA (#49642)

* `widenconst` before type check in SROA These days, mutable structs can be `PartialStruct` if one of the fields is annotated as `const`, so we need to widenconst before this check. * Update test/compiler/irpasses.jl Co-authored-by: Shuhei Kadowaki <[email protected]> --------- Co-authored-by: Shuhei Kadowaki <[email protected]>
JuliaLang · May 5, 2023 · f4d9416 · f4d9416
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diff --git a/base/compiler/ssair/passes.jl b/base/compiler/ssair/passes.jl
@@ -1265,6 +1265,7 @@ function sroa_mutables!(ir::IRCode, defuses::IdDict{Int, Tuple{SPCSet, SSADefUse
         typ = unwrap_unionall(ir.stmts[newidx][:type])
         # Could still end up here if we tried to setfield! on an immutable, which would
         # error at runtime, but is not illegal to have in the IR.
+        typ = widenconst(typ)
         ismutabletype(typ) || continue
         typ = typ::DataType
         # First check for any finalizer calls

diff --git a/test/compiler/irpasses.jl b/test/compiler/irpasses.jl
@@ -1230,3 +1230,18 @@ let src = code_typed1(named_tuple_elim, Tuple{Symbol, Tuple})
           count(iscall((src, Core._svec_ref)), src.code) == 0 &&
           count(iscall(x->!isa(argextype(x, src).val, Core.Builtin)), src.code) == 0
 end
+
+# Test that sroa works if the struct type is a PartialStruct
+mutable struct OneConstField
+    const a::Int
+    b::Int
+end
+
+@eval function one_const_field_partial()
+    # Use explicit :new here to avoid inlining messing with the type
+    strct = $(Expr(:new, OneConstField, 1, 2))
+    strct.b = 4
+    strct.b = 5
+    return strct.b
+end
+@test fully_eliminated(one_const_field_partial; retval=5)